Plank jacks are a combined cardio and core-strengthening exercise. They can help you strengthen the muscles of both the upper and lower body. Adding plank jacks to your exercise routine a few times a week may also increase core strength and stability, burn calories, and help reduce fat.

Read on to learn more about the benefits, safety tips, and steps to perform a plank jack.

To perform a plank jack, follow these steps:

  1. Start in plank position with your arms extended and hands under your shoulders, feet together. Your body should be in a straight line from your head to your heels.
  2. Engage your abs to help protect your lower back from injury.
  3. Jump both feet out wide to each side as if you were doing a horizontal jumping jack.
  4. Stay in plank position as you quickly jump your feet back together.
  5. Continue to jump back in and out. Keep your back flat and don’t let your hips drop throughout the entire movement. Your arms should remain steady.
  6. Perform plank jacks for 10–20 seconds to start. You can work up to 60 seconds or jump at a faster speed to make the move more challenging.

You can also perform plank jacks on your forearms for an additional challenge.

You can perform plank jacks without “jumping” your legs out to the side. This version is called plank side taps. Plank side taps are a beginner-friendly, low-impact exercise.

Plank side taps

  1. Start in a plank position with your arms extended and hands under your shoulders. Feet should be together and your body should be in a straight line from your head to your heels.
  2. Engage your abs by pulling them in.
  3. Step your right foot out to the side. Bring it back to center.
  4. Step your left foot out to the side. Bring it back to center.
  5. Perform 8–10 reps on each leg.

Plank jacks can help strengthen the following muscles:

  • chest
  • abdominals
  • back
  • shoulders
  • arms

Strengthen core muscles

Plank jacks may help strengthen the muscles of the core. Plank and plank variation exercises activate all the core muscles, including the rectus abdominis, transverse abdominis, and obliques. They also activate the muscles in the hips and back.

Results from one small study with 14 participants found that forearm planks required double the activation of the abdominal muscles compared to other core strengthening exercises, such as crunches.

The researchers concluded that performing planks can lead to improved stability, reduced risk for injury, and maintenance of mobility.

Prevent back pain

Strengthening the core muscles may also help reduce risk for lower back pain. A strong core is important for proper spinal alignment. That, in turn, reduces your risk for back injuries.

If you have existing back pain, plank jacks may help with that, too. Results from a 2017 clinical trial showed that six weeks of core stabilization exercises were more effective than other physical therapy exercises for alleviating low back pain. There were 120 participants in the study between the ages of 20 and 60, and they all had nonspecific chronic lower back pain.

While plank jacks weren’t included in the core-stabilizing exercises, participants did incorporate front and side planks into their routines. Because plank jacks are a core stabilizing exercise, you may be able to see similar results by adding this exercise to your routine.

However, more research is needed to see how core-stabilization exercises affect a larger group of people and the effect they can have on chronic back pain related to specific conditions or injuries.

Burn calories and fat

Plank jacks are a cardiovascular exercise. Cardiovascular exercises can help you to burn calories and regulate your weight. They may also help lower blood pressure and reduce your risk for heart disease.

To safely perform plank jacks, follow these tips:

  • Engage your core throughout the entire move. This can help to protect the lower back from injury.
  • Keep your body in a straight line and don’t let your hips dip.
  • Stop if you feel fatigued, dizzy, or overheated.

Plank position can put stress on the wrists. Plank jacks should be avoided or modified if you have a wrist injury or wrist pain. To modify, you can perform them on your forearms instead.

Plank jacks may help strengthen the core muscles and alleviate lower back pain, but you should talk to your doctor before doing this exercise if you have a back, shoulder, or other injury.

Plank jacks are a moderate- to high-intensity aerobic activity. They’re also a muscle-strengthening activity. The U.S. Department of Health and Human Services recommends that healthy adults should aim to get at least 150 minutes of moderate-intensity aerobic physical activity each week and do muscle-strengthening activities two days a week.

Because plank jacks are both an aerobic and a resistance exercise, you can add them to your routine in a few ways, including:

Sample routine

The following is an example routine for how you can add plank jacks to a HIIT workout. Perform each exercise for 20–60 seconds. Rest for 30–60 seconds between exercises. Repeat up to 4 times.

  1. High knee running. To do this exercise, run in place while lifting your knees as high as possible.
  2. Plank jacks.
  3. Squat jumps. Stand with your feet hip width apart. Slowly squat down. As you rise back up out of the squat, add a jump before going back into your squat.
  4. Ankle touches. Lie on your back with your knees bent, feet flat on the floor, and your arms by your side. Lift your head off the ground and reach your right hand towards your right ankle. As you return your right hand back to the starting position, extend your left hand towards your left ankle. Repeat.
  5. Burpees. Stand with feet shoulder-width apart and then squat down. When you reach the bottom of your squat, place your hands on the floor, shift your weight to your upper body, and jump your feet back, landing in a plank position. Immediately hop back to your low squat position and then return to standing and then add a jump before returning to the squat position.

Plank jacks are an effective exercise for working core muscles while also getting the benefits of cardio exercise.

Plank jacks can be combined with other cardio and core exercises for a complete workout. Try adding them to your core or HIIT routine a few times a week. Just remember to always check with your doctor before adding new cardio workouts to your routine.